TRISO Fuel Qualification Modeling and Experiment Design

As TRISO-coated nuclear fuels are increasingly planned for use in forthcoming commercial reactor designs, qualification strategies for the fuel form are of increasing interest. In the shortterm, it is expected that U.S. based reactor developers will collect irradiation experiment data for their TRISO fuel designs that deviate in any product specifications or extend outside of the operational envelope of the Department of Energy’s Advanced Gas Reactor TRISO fuel qualification program. In the future, it may be possible to qualify TRISO fuels with a combination of increased regulatory guidance drawn from additional licensing experience with the fuel form, experiment data for TRISO with greater variations in product or operational envelopes than that qualified today, and evaluation models for which confidence in modeling and simulation tools’ abilities to predict fission product release is crucial. High-quality validation of simulation tools used to generate evaluation models requires experiment data from a variety of sources with different products under many conditions. This work addresses the lack of confidence in TRISO simulation capability by validating the method developed in Phase I with existing experiment data as well as designing and modeling a future irradiation campaign for TRISO fuel with modest product specifications differences from those of the Advanced Gas Reactor program. Previous work developed a multi-scale, multi-physics fuel performance simulation capability called the Single Particle Per Element Method by coupling TRISO failure predictions from a publicly funded fuel performance code to a commercially developed digital twin simulation engine. This approach provides a method to predict fission product release for transient events that prismatic, high temperature gas-cooled reactors may encounter such as blocked coolant channels, loss-of-flow, overcooling, and reactivity insertions at any user-specified spatial resolution or level of simulation fidelity. While Phase I of the project demonstrated the approach’s flexibility and wide application, Phase II will validate the method using existing experiment data with comparisons to results from validation studies previously undertaken with the experiment data while expanding the internally developed simulation engine’s capability to inform regulatory interests with PRA assessments and environmental modeling enabling dose consequence calculation. By partnering with a national laboratory, the Phase II will also provide a path to design and model a confirmatory irradiation campaign that will provide full burnup qualification experiment data for a commercial fuel product specification. Through continuing development of the Single Particle Per Element Method from Phase I, this work will illustrate the ease of commercial adoption of publicly developed tools into commercially developed modeling software, validate the new method with experiment data, and work towards obtaining fuel experiment data that may be used to further validate simulation predictions and qualify TRISO fuel for a portable microreactor.